1. Field of the Invention
The present invention relates to anti-siphon valves and, more particularly, to a siphon breaker having a check valve and a butterfly valve.
2. Description of Related Art
Siphons are used for many purposes, such as to drain or fill ponds, provide a water-source to a desired location, or to generally move ground water. A siphon is a continuous pipe, hose, or tube that allows liquid to drain from a body of liquid through an intermediate point that is higher than the body of liquid. The up-slope flow of a siphon through the elevated intermediate point is driven by hydrostatic pressures and does not require pumping. In operation, the pipe must have a first end submerged in the body of liquid and a second end positioned at a location that is lower than the body of liquid. As the liquid drains out of the pipe at the lower end, a vacuum is formed within the pipe that draws the liquid from the body of liquid through the elevated intermediate point.
In certain pumping operations, a pump is configured to pump liquid from a lower level to a body of liquid at a higher level. If the pump fails or is interrupted in some manner, the liquid-pressure within the pumping system is lessened. Consequently, a back-siphon can form in which liquid at the lower end of the pipe can draw liquid from the body of liquid at the higher level. This is particularly of concern when a siphon connects a plumbing system with a reservoir, or when a siphon connects an area to be drained with a lake or ocean reservoir. As water, or other liquid, is delivered to other areas of the plumbing system during use, the pressure within the system may be lessened and water, or other liquid, can be drawn back out of the reservoir through a back-siphon. This can cause contamination of the plumbing system and/or unintentional flooding of the area.
Consequently, there is a need for an improved anti-siphon valve which prevents the backward flow of liquid from a reservoir into a plumbing system.